Fusion weld defect detection probe, device and method based on magnetic field signal measurement

Abstract

The present invention discloses a probe, device and method for detecting defects in fusion welds based on magnetic field signal measurement, which solves the problem in the prior art that fusion welds with complex structures, special positions and coarse grain materials cannot achieve full coverage in-situ non-destructive detection effects. The detection probe specifically includes a detection shell and a sensor installed in the detection shell; the sensor includes a detection core, a first detection coil, a second detection coil, a first signal line for outputting a magnetic field signal of the first detection coil and a second signal line for outputting a magnetic field signal of the second detection coil; the detection core is arranged near one end of the detection shell; the first detection coil and the second detection coil are sequentially wound outside the detection core along the direction from one end of the detection shell to the other end of the detection shell; a mutual interference-free distance a is provided between the first detection coil and the second detection coil; the mutual interference-free distance a is used to avoid mutual interference between the magnetic field signal of the first detection coil and the magnetic field signal of the second detection coil.

Description

Technical Field

[0001] The present invention relates to the technical field of fusion weld defect detection, and in particular to a fusion weld defect detection probe, device and method based on magnetic field signal measurement. Background Art

[0002] The main methods for detecting defects in fusion welds include X-ray detection, ultrasonic detection and eddy current detection technology. X-ray detection uses electromagnetic waves or electromagnetic radiation to interact with materials in the process of penetrating objects. It determines whether there are defects in the weld by detecting the transmission intensity, and evaluates the location and size of the defects. Ultrasonic testing uses the difference in acoustic properties of the workpiece material and its defects to reflect the ultrasonic propagation waveform and the energy change of the penetration time to detect internal defects in the weld. Eddy current testing uses the fact that defects affect the electrical conductivity and magnetic permeability of the workpiece material, thereby affecting the intensity and distribution of the eddy current field excited by the eddy current probe, and identifies defects based on the changes in the electrical characteristics of the probe caused by the combined effect of the probe and the eddy current field.

[0003] For a large number of weld seams on aerospace engines or special equipment, it is impossible to perform radiographic or ultrasonic testing due to structural reasons. In particular, after welding, the overall structure of the components is complex and the volume is large. The weld seams in many locations are in the detection blind area and cannot be inspected. Therefore, the main problem of weld seam defect detection is to achieve full coverage in-situ detection of weld seams and ensure the safe operation of equipment. Radiographic detection cannot penetrate weld seams in some special locations or the film cannot be placed, resulting in insufficient detection coverage and inability to achieve full coverage in-situ detection. Ultrasonic testing has certain requirements for the surface of the workpiece, and the surface of the weld seam is generally rough. The surface of the workpiece needs to be pretreated before detection, which increases the detection cost; and the detection effect is poor for materials such as austenite, martensite, and duplex stainless steel with coarse grains; in the case of weld seams with a lock bottom, the lock bottom becomes the reflection interface of the ultrasonic wave, and ultrasonic testing loses its meaning. Eddy current testing can only detect defects on the surface and near the surface of conductive materials, resulting in the inability to detect or poor detection effect for weld seams with thicker thickness, and the detection results are also easily affected by the material itself and other factors.

[0004] Therefore, there is an urgent need for a fusion weld defect detection device that can perform full-coverage in-situ non-destructive testing on fusion welds with complex structures, special locations, and coarse-grained materials. Summary of the invention

[0005] The purpose of the present invention is to provide a fusion weld defect detection probe, device and method based on magnetic field signal measurement, which solves the problem in the prior art that fusion welds with complex structures, special locations and coarse grains cannot achieve full coverage in-situ non-destructive detection effects.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] In a first aspect, the present invention provides a fusion weld defect detection probe based on magnetic field signal measurement, which is used to detect fusion weld defects of ferromagnetic materials or weak magnetic materials, and is special in that it includes a detection housing, a sensor installed in the detection housing;

[0008] The sensor comprises a detection core, a first detection coil, a second detection coil, a first signal line for outputting a magnetic field signal of the first detection coil, and a second signal line for outputting a magnetic field signal of the second detection coil; the first signal line and the second signal line are used to connect to an external industrial computer respectively;

[0009] The detection magnetic core is arranged close to one end of the detection housing;

[0010] The first detection coil and the second detection coil are wound around the detection magnetic core in sequence along a direction from one end of the detection shell to the other end of the detection shell; a mutual interference-free distance a is provided between the first detection coil and the second detection coil; the mutual interference-free distance a is used to avoid mutual interference between the magnetic field signal of the first detection coil and the magnetic field signal of the second detection coil.

[0011] In combination with the first aspect, in a possible implementation manner, the first detection coil and the second detection coil have the same length and the same winding direction;

[0012] The length of the first detection coil and the second detection coil is 5mm-7mm.

[0013] In combination with the first aspect, in a possible implementation manner, an adjustment button is provided on the detection housing;

[0014] The action end of the adjustment button extends into the detection housing to tighten the detection magnetic core.

[0015] In combination with the first aspect, in a possible implementation manner, the adjustment button is a nylon screw;

[0016] The nylon screw is threadedly connected to the detection housing.

[0017] In combination with the first aspect, in a possible implementation manner, a detection switch is further provided on the detection housing;

[0018] The detection switch is installed on one end of the detection housing away from the detection magnetic core, and is connected to an external industrial computer through a control line, and is used to control the on and off of the first signal line and the second signal line.

[0019] In combination with the first aspect, in a possible implementation manner, the material of the detection switch is austenitic stainless steel.

[0020] In combination with the first aspect, in a possible implementation, the detection housing includes a detection portion, a clamping portion, and a cable portion which are sequentially connected and whose diameters increase sequentially;

[0021] One end of the detection magnetic core is located in the detection part, and the other end extends into the clamping part;

[0022] The adjusting button is mounted on the clamping portion and is close to the detecting portion;

[0023] A cable buckle is arranged inside the cable part; the cable buckle is fixed on the inner wall of the cable part and is used to lock the first signal line, the second signal line and the control line connected to the detection switch.

[0024] In a second aspect, the present invention further provides a fusion weld defect detection device based on magnetic field signal measurement, which is special in that it includes an industrial computer and a fusion weld defect detection probe based on magnetic field signal measurement as in the first aspect and any possible implementation thereof;

[0025] The first detection coil and the second detection coil are used to collect magnetic field signals of the fusion weld;

[0026] The first signal line and the second signal line are connected to the industrial computer through aviation plug terminals respectively;

[0027] The industrial computer is used to process the magnetic field signal.

[0028] In a third aspect, the present invention further provides a method for detecting fusion weld defects based on magnetic field signal measurement, based on the above-mentioned fusion weld defect detection device based on magnetic field signal measurement, which is special in that it includes the following steps:

[0029] Step 1, place the detection probe perpendicular to the surface of the weld to be detected, and move the detection probe at a constant speed along the detection path for scanning to obtain a first detection curve of the first detection coil and a second detection curve of the second detection coil; the detection path is set along the length direction of the weld to be detected; the abscissa of the first detection curve and the second detection curve are both the length of the detection path, and the ordinate is both the magnetic induction intensity;

[0030] Step 2: judging whether there is a defect according to the first detection curve and the second detection curve;

[0031] 2.1. Determine the causes of the magnetic signals of the first detection curve and the second detection curve:

[0032] When the absolute values ​​of the slopes of the same horizontal coordinate of the first detection curve and the second detection curve in any horizontal coordinate interval are both less than the fixed value k or the absolute values ​​of the slopes are greater than the fixed value k, it is determined that the magnetic signal in the horizontal coordinate interval is caused by residual stress; the fixed value k is determined by the comparison test block;

[0033] When the absolute value of the slope of the first detection curve in any horizontal axis interval is greater than the fixed value k, and the absolute value of the slope of the second detection curve in the horizontal axis interval is less than the fixed value k, it is determined that the magnetic signal in the interval is caused by a defect;

[0034] 2.2. Determine whether the defect is a weld defect:

[0035] The defect is within the horizontal axis interval determined in step 2.1;

[0036] If the length of the first detection curve in the horizontal axis interval is within the calibration length range of the currently inspected weld, and at the same time, the maximum change in the magnetic induction intensity on the vertical axis is greater than the minimum threshold of the magnetic induction intensity corresponding to the current material and less than the maximum threshold of the magnetic induction intensity corresponding to the current material, it is determined that the defect is a weld defect; the calibration length range of the currently inspected weld is determined according to the thickness of the inspected weld;

[0037] Step 3: Determine the position of the weld defect according to the horizontal coordinate interval corresponding to the weld defect.

[0038] In combination with the first aspect, in a possible implementation, before step 1, the method further includes a step of fine-tuning the relative position of the sensor in the detection probe and the detection housing before detection;

[0039] In step 1, the detection path includes at least one single detection path, and the calibration method of the single detection path is specifically as follows: the single detection paths are calibrated sequentially along the length direction of the weld to be detected, and the length range of each single detection path is 100mm-200mm. A repeated detection area is provided between two adjacent single detection paths, and the repeated detection area is greater than or equal to 1 / 3 of the length of the single detection path.

[0040] The beneficial effects of the present invention are:

[0041] 1. The fusion weld defect detection probe based on magnetic field signal measurement provided by the present invention has a detection core arranged in a detection shell, and a first detection coil and a second detection coil wound on the detection core. The fusion weld defects of ferromagnetic materials or weakly magnetic materials are detected simultaneously and synchronously by the first detection coil and the second detection coil. It is capable of performing full coverage in-situ nondestructive testing on fusion welds with complex structures and special positions, eliminating the influence of residual stress in the weld, and realizing effective identification and defect location of welding defects.

[0042] 2. The fusion weld defect detection probe based on magnetic field signal measurement provided by the present invention can identify and locate weld defects in fusion welds of coarse-grained materials and those with a lock bottom structure.

[0043] 3. The first detection coil and the second detection coil in the fusion weld defect detection probe of the present invention have the same length and winding direction, so that the comparison of the two detection curves based on the same position is more accurate, and the weld defects identified and located are more accurate.

[0044] 4. The present invention also provides an adjustment button on the detection shell for tightening the detection core; thus, the distance between the end of the detection core and the port of the detection shell can be adjusted according to the specific conditions of the weld seam to accommodate more different weld seams.

[0045] 5. The adjustment button in the present invention is a nylon screw, which can avoid affecting the detection signal and ensure the accuracy of the detection result.

[0046] 6. In the present invention, a detection switch for controlling the on / off of the first signal line and the second signal line is also provided on the detection housing, which is easy to operate.

[0047] 7. The detection housing of the present invention is composed of a detection part, a clamping part and a cable part with successively increasing diameters. In this way, the detection part with a smaller diameter is convenient for scanning the weld seam, the clamping part with a moderate diameter is convenient for hand-holding or clamping by a robotic arm, and the cable part with a larger diameter is convenient for accommodating cables. This structure is reasonable and applicable.

[0048] 8. The weld defect detection device provided by the present invention has a small overall structure and is easy to carry. It can detect welds of ferromagnetic materials or weakly magnetic materials in a natural environment and has a wider applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a cross-sectional view of a fusion weld defect detection probe based on magnetic field signal measurement provided by an embodiment of the present invention;

[0050] Figure 2 is a schematic diagram of the connection structure between the detection magnetic core, the first detection coil and the second detection coil provided in an embodiment of the present invention;

[0051] Figure 3 is a schematic structural diagram of a detection housing provided in an embodiment of the present invention;

[0052] Figure 4 It is a structural schematic diagram of a fusion weld defect detection device based on magnetic field signal measurement provided by an embodiment of the present invention;

[0053] Figure 5 A schematic diagram of the structure of an industrial computer provided in an embodiment of the present invention;

[0054] Figure 6 These are the performance diagrams of two types of first detection curves and second detection curves that often appear in the embodiments of the present invention;

[0055] Figure 7 This is a curve diagram of the change of magnetic induction intensity of a weld detected when the base material is martensitic stainless steel in an embodiment of the present invention;

[0056] Figure 8 The actual defect location information of the weld whose base material is martensitic stainless steel obtained by X-ray filming.

[0057] In the figure, 1-detection housing, 11-adjustment button, 12-detection switch, 13-detection part, 14-clamping part, 15-cable part, 151-cable buckle;

[0058] 2-sensor, 21-detection core, 22-first detection coil, 23-second detection coil;

[0059] 3-industrial computer, 31-display screen, 32-keyboard, 33-touch pad, 34-control switch, 35-industrial computer mainboard, 36-battery pack, 37-magnetic field signal acquisition board.

[0060] 4 - first detection curve, 5 - second detection curve. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Magnetic detection technology is a non-destructive testing technology based on magnetic field signal measurement, such as metal magnetic memory, Barkhausen noise, etc., and is currently mainly used for the detection of fatigue damage of ferromagnetic materials. The fusion weld defect detection probe, device and method based on magnetic field signal measurement provided in the embodiments of the present invention are mainly used for detecting ferromagnetic materials, such as martensitic and duplex stainless steel, or weak magnetic materials, such as austenitic stainless steel.

[0063] The following is a detailed description of a fusion weld defect detection probe based on magnetic field signal measurement provided by an embodiment of the present invention.

[0064] Figure 1 A cross-sectional view of a fusion weld defect detection probe based on magnetic field signal measurement provided by an embodiment of the present invention, Figure 2 is a schematic diagram of the connection structure between the detection core, the first detection coil and the second detection coil provided by the present invention, combined with Figure 1 and Figure 2 As shown, the detection probe may include: a detection shell 1, a sensor 2 installed in the detection shell 1; the sensor 2 may include a detection core 21, a first detection coil 22, a second detection coil 23, a first signal line for outputting a magnetic field signal of the first detection coil 22, and a second signal line for outputting a magnetic field signal of the second detection coil 23; the first signal line and the second signal line are used to connect to an external industrial computer 3 respectively; the detection core 21 is arranged near one end of the detection shell 1; the first detection coil 22 and the second detection coil 23 are sequentially wound around the detection core 21 along a direction from one end of the detection shell 1 to the other end of the detection shell 1; an interference-free distance a is provided between the first detection coil 22 and the second detection coil 23; the interference-free distance a is used to avoid mutual interference between the magnetic field signal of the first detection coil 22 and the magnetic field signal of the second detection coil 23.

[0065] It can be understood that the sensor 2 is a magnetic field signal acquisition sensor array composed of a first detection coil 22 and a second detection coil 23, and its detection sensitive direction is the end face of the detection core 21. The use of a common magnetic core gradient sensor array can effectively reduce the length of the sensor, thereby ensuring the lifting distance of the second detection coil 23 relative to the surface of the weld to be detected, so as to eliminate the influence of residual stress in the weld. In addition, it is also convenient to detect the overall packaging and calibration of the magnetic core 21, the first detection coil 22 and the second detection coil 23, ensuring good sensitivity and performance consistency of the sensor. Through actual performance testing, the mutual interference-free distance a is determined to ensure that the magnetic field signals between the first detection coil 22 and the second detection coil 23 do not interfere with each other. The length of the first signal line and the second signal line can be reserved according to the structure of the actual detection object.

[0066] The detection probe provided in the embodiment of the present invention can simultaneously obtain the magnetic field signals of the first detection coil 22 and the second detection coil 23, that is, it can obtain the magnetic field signals of different lifting distances at the same position on the surface of the weld at the same time. As a supplement to the existing detection technology, it can achieve full coverage in-situ detection of weld defects at special positions with high detection efficiency. It has application space in industrial fields such as aerospace, special equipment, etc., and is of great significance to ensure the safe operation of equipment.

[0067] Optionally, the first detection coil 22 and the second detection coil 23 have the same length and the same winding direction; the length of the first detection coil 22 and the second detection coil 23 is 5 mm-7 mm.

[0068] It should be noted that the length of the first detection coil 22 and the second detection coil 23 cannot be too long or too short. If it is too long, the detection signal of the second detection coil 23 will be invalid, and if it is too short, the detection accuracy of the first detection coil 22 and the second detection coil 23 cannot be guaranteed.

[0069] An adjusting button 11 is provided on the detection housing 1 ; the action end of the adjusting button 11 extends into the detection housing 1 to tighten the detection magnetic core 21 .

[0070] The adjustment button 11 is a nylon screw; the nylon screw is threadedly connected to the detection housing 1 .

[0071] The sensor 2 can be adjusted by the nylon screw, thereby adjusting the lifting distance of the first detection coil 22 and the second detection coil 23 relative to the surface of the weld seam and fixing the sensor 2.

[0072] A detection switch 12 is also provided on the detection housing 1 ; the detection switch 12 is installed at one end of the detection housing 1 away from the detection magnetic core 21 , and is used to control the on / off of the first signal line and the second signal line.

[0073] The detection switch 12 is installed on the detection housing 1 at one end away from the detection magnetic core 21 to ensure that there is no influence on the detected magnetic field signal, and the detection switch 12 can be pressed by the thumb while holding the detection housing 1 with one hand, which is convenient for operation. The detection switch 12 is connected to the external industrial computer 3 through a control line, and the material of the detection switch 12 is austenitic stainless steel.

[0074] Specifically, the detection switch 12 is made of austenitic stainless steel with very weak magnetism.

[0075] Figure 3 Schematic diagram of the structure of the detection housing provided by the present invention; Figure 3 As shown, the detection housing 1 includes a detection part 13, a clamping part 14 and a cable part 15 which are connected in sequence and have increasing diameters in sequence; one end of the detection core 21 is located in the detection part 13, and the other end extends into the clamping part 14; the adjustment button 11 is installed on the clamping part 14 and is close to the detection part 13; a cable buckle 151 is arranged in the cable part 15; the cable buckle 151 is fixed on the inner wall of the cable part 15, and is used to lock the first signal line, the second signal line and the control line connected to the detection switch 12.

[0076] In order to facilitate hand-held detection probe or use of a robotic arm to clamp the detection probe, the entire detection housing 1 adopts a diameter reduction processing method. The detection part 13 is thinner for detection and scanning, the clamping part 14 is slightly thicker for hand-held or robotic arm clamping, and the cable part 15 is thicker so that there is enough space to install switches and wiring. A cable buckle 151 is provided in the cable part 15 to lock the cable to prevent the cable from being subjected to force and causing the detection core 21, the first detection coil 22 and the second detection coil 23 to shift.

[0077] Figure 4 is a structural schematic diagram of a fusion weld defect detection device based on magnetic field signal measurement provided by the present invention, such as Figure 4As shown, it includes an industrial computer 3 and the above-mentioned weld defect detection probe based on magnetic field signal measurement; the first detection coil 22 and the second detection coil 23 are used to collect the magnetic field signal of the weld; the first signal line and the second signal line are respectively connected to the industrial computer 3 through the aviation plug terminal; the industrial computer 3 is used to process the magnetic field signal, and its supporting upper computer software can realize the functions of real-time collection, display, storage and data processing of detection data. The data processing function is mainly to eliminate the influence of residual stress of the fusion weld and realize the effective identification and defect location of fusion welding defects.

[0078] Figure 5 A schematic diagram of the structure of an industrial computer provided in an embodiment of the present invention is shown in FIG. Figure 5 As shown, the chassis of the industrial computer 3 includes a display screen 31, a keyboard 32, a touch panel 33 and a control switch 34. The chassis includes an industrial computer mainboard 35, a battery pack 36 and a magnetic field signal acquisition board 37.

[0079] It is worth noting that the message between the industrial computer control center and the magnetic field signal acquisition board 37 uses the transmission protocol of the Ethernet port or the USB interface to decode and transmit the collected magnetic field signal data to the industrial computer 3.

[0080] The detection principle of the present invention is as follows:

[0081] The magnetic detection technology used in the present invention is a kind of magnetic field signal, that is, the physical quantity of magnetic induction intensity (unit, Tesla, T, actual measurement is generally nT, 1nT = 10 -9 T) measurement non-destructive testing technology. This magnetic detection technology does not require the application of an excitation field source during implementation, and can be implemented in a natural magnetic field environment. The change in the environmental magnetic field is generally less than 10nT, which is much smaller than the magnetic anomaly signal generated by the defect. If there is a macro defect in the molten weld, there is an inhomogeneity between the defect and the surrounding weld structure, which will cause abnormal changes in the magnetic field signal at the defect. If there is residual stress in the molten weld, abnormal changes in the magnetic field signal will also occur at the location of stress concentration. By scanning the surface or near the surface of the molten weld with a detection probe, the change in magnetic induction intensity is collected to determine whether there are defects or stresses in the molten weld, and the change law of the magnetic induction intensity is analyzed and compared to obtain defect information in the molten weld. This method can be applied to the detection of molten welds of ferromagnetic and weakly magnetic materials, including but not limited to austenite, martensite, duplex stainless steel and other materials.

[0082] The specific detection methods are introduced in detail below:

[0083] Based on the above-mentioned fusion weld defect detection device based on magnetic field signal measurement, an embodiment of the present invention further provides a fusion weld defect detection method based on magnetic field signal measurement, comprising the following steps:

[0084] Step 1: Fine-tune the relative position of the sensor in the detection probe and the detection housing.

[0085] Specifically, fine-tune the nylon screw according to the residual height and roughness of the weld surface to be detected, adjust the relative position of the end face of the sensor in the measuring probe and the end face of the detection shell, connect the first signal line and the second signal line to the industrial computer through the aviation plug terminal, connect the industrial computer to the power supply, start the industrial computer, make the industrial computer run stably, turn on the control switch of the magnetic field signal acquisition board, and preheat for at least 10 minutes.

[0086] Step 2, the step of calibrating the single detection path, specifically: calibrate the single detection paths in sequence along the length direction of the weld to be detected, the length of each single detection path ranges from 100mm to 200mm, and a repeated detection area is provided between two adjacent single detection paths, and the repeated detection area is greater than or equal to 1 / 3 of the length of the single detection path. A detection path includes at least one single detection path;

[0087] Step 3, place the detection probe perpendicular to the surface of the weld to be detected, and move the detection probe at a uniform speed along the detection path for scanning to obtain a first detection curve of the first detection coil and a second detection curve of the second detection coil; the detection path is set along the length direction of the weld to be detected; the abscissas of the first detection curve and the second detection curve are both the length of the detection path, and the ordinates are both the magnetic induction intensity.

[0088] Specifically, place the detection probe perpendicular to the surface of the weld to be detected, press the detection switch, start data collection, and move the detection probe at a uniform speed along the detection path for scanning. After the detection path is scanned, press the detection switch again, stop data collection, and save it to the specified storage path synchronously. The collected data is analyzed and processed by software: the collected data is evenly filled according to the length of the detection path, that is, the horizontal axis can be converted into the length information of the detection path for display, and the vertical axis is the magnetic induction intensity data of the first detection curve and the second detection coil. The positive and negative signs indicate that the directions of the detection magnetic field are opposite, and the numerical value indicates the magnitude of the magnetic induction intensity, thereby forming the first detection curve and the second detection curve on the coordinate axis.

[0089] Step 4: judging whether there is a defect according to the first detection curve and the second detection curve;

[0090] 4.1. Determine the causes of the magnetic signals of the first detection curve and the second detection curve:

[0091] When the absolute values ​​of the slopes of the first detection curve and the second detection curve in the same horizontal coordinate in any horizontal coordinate interval are both less than the fixed value k or the absolute values ​​of the slopes are greater than the fixed value k, it is determined that the magnetic signal in the horizontal coordinate interval is caused by residual stress; the fixed value k is determined by the comparison test block;

[0092] When the absolute value of the slope of the first detection curve in any horizontal axis interval is greater than the fixed value k, and the absolute value of the slope of the second detection curve in the horizontal axis interval is less than the fixed value k, it is determined that the magnetic signal in the interval is caused by a defect.

[0093] 4.2. Determine whether the above defects are weld defects:

[0094] The defect is within the horizontal axis interval determined in step 4.1;

[0095] If the length of the first detection curve in the horizontal axis interval is within the calibrated length range of the current inspected weld, and at the same time, the maximum change in the magnetic induction intensity on the vertical axis is greater than the minimum threshold value of the magnetic induction intensity corresponding to the current material and less than the maximum threshold value of the magnetic induction intensity corresponding to the current material, the above defect is determined to be a weld defect; the calibrated length range of the current inspected weld is determined according to the thickness of the inspected weld; it should be noted that the maximum threshold and minimum threshold values ​​of the magnetic induction intensity corresponding to the current material are determined by the comparison test block, and usually the maximum threshold is related to the variation range of the magnetic induction intensity of the overall magnetic signal of the comparison test block, and the minimum threshold is related to the base noise of the test block.

[0096] Step 5: Determine the location of the weld defect according to the horizontal axis interval corresponding to the weld defect.

[0097] Specifically, a rectangular frame is used to frame the weld defect determined in step 4.2 on the first detection curve and the second detection curve, and the horizontal axis interval corresponding to the rectangular frame is found, and the position of the weld defect is determined according to the horizontal axis interval.

[0098] For example, Figure 6 2 are the performance diagrams of the two first detection curves and the second detection curves that often appear in the embodiments of the present invention. Figure 6 As shown, M is the weld surface. Figure 6In the left and right figures, the length of the first detection curve 4 in the horizontal axis interval is within the calibrated length range of the current weld to be inspected. At the same time, the maximum change of the magnetic induction intensity in the vertical axis is greater than the minimum threshold of the magnetic induction intensity corresponding to the current material and less than the maximum threshold of the magnetic induction intensity corresponding to the current material. In these two cases, the first detection curve 4 has a sudden change, indicating that the magnetic induction intensity data collected by the first detection coil 22 has a sudden change, while the second detection curve 5 remains basically stable, indicating that the magnetic induction intensity data collected by the second detection coil remains basically stable. It can be understood that point A and point B are the critical points for the first detection coil 22 and the second detection coil 23 to enter and leave the influence range of the weld defect during the detection process, that is, the position from point A to point B is the starting and ending position of the magnetic anomaly span S. The actual defect position is within the range of the magnetic anomaly span S, and the actual length L of the defect is less than the span S. Assuming that the diameter of the sensor end face is Ф, the angle between the conical surface of the sensor coverage range and the length direction of the fusion weld is approximately 45°, and the burial depth of the defect is H, then the actual length of the defect L≈S-2H-Ф. It can be understood that the larger the span S of the magnetic field signal magnetic anomaly is, the larger the burial depth H and length L of the defect are. It is worth noting that if the marked magnetic anomaly span is less than the minimum value of the calibrated length range of the current weld being inspected, or the magnetic anomaly span is greater than the maximum value of the calibrated length range of the current weld being inspected, it is considered that this is a magnetic anomaly caused by non-defects.

[0099] The following is an introduction to the detection method for a specific test block material:

[0100] Test block material: Flat butt fusion weld test block, the base material is martensitic stainless steel, and the welding wire material has similar magnetic properties to the base material. There are two defects on the fusion weld, the test block size is 200mm*100mm*10mm, the weld excess height is 2mm, the weld thickness is 10mm, the fixed value k determined by the comparison test block is 2500, the current calibration length range of the weld being tested is 13mm-48mm, the minimum threshold of the magnetic induction intensity corresponding to the material is 5000nT, and the maximum threshold of the magnetic induction intensity corresponding to the material is 50000nT.

[0101] The test steps for this test block are as follows:

[0102] Step 1. Fine-tune the nylon screw according to the residual height and roughness of the weld surface to be detected, so as to adjust the relative position between the end face of the sensor and the end face of the detection shell. Connect the first signal line and the second signal line to the industrial computer through the aviation plug terminal, connect the industrial computer to the power supply, start the industrial computer, and after the industrial computer runs stably, turn on the control switch of the magnetic field signal acquisition board and preheat for at least 10 minutes.

[0103] Step 2: calibrate a single detection path along the detection path in the length direction of the weld to be detected. The detection path includes a single detection path, and the single detection path is the same as the weld length, which is 200 mm.

[0104] Step 3: Place the detection probe perpendicular to the surface of the weld to be detected, and move the detection probe at a constant speed along the calibrated single detection path for scanning to obtain a first detection curve of the first detection coil and a second detection curve of the second detection coil.

[0105] Step 4: judging whether there is a defect according to the first detection curve and the second detection curve;

[0106] 4.1. Determine the causes of the magnetic signals of the first detection curve and the second detection curve:

[0107] When the absolute values ​​of the slopes of the first detection curve and the second detection curve at the same horizontal coordinate in any horizontal coordinate interval are both less than the fixed value k2500 or the absolute values ​​of the slopes are greater than the fixed value k2500, it is determined that the magnetic signal in the horizontal coordinate interval is caused by residual stress;

[0108] When the absolute value of the slope of the first detection curve in any horizontal axis interval is greater than the fixed value k2500, and the absolute value of the slope of the second detection curve in the horizontal axis interval is less than the fixed value k2500, it is determined that the magnetic signal in the interval is caused by a defect;

[0109] It should be noted that the absolute value of the slope of the first detection curve in any horizontal axis interval is greater than the fixed value k2500. It may be that the absolute value of the slope is greater than the fixed value k2500, or there may be more than two points where the slope suddenly changes. At these mutation points, the absolute value of the slope is greater than the fixed value k2500. The range of the magnetic anomaly is delineated based on these mutation points.

[0110] 4.2. Determine whether the above defects are weld defects:

[0111] The defect is within the horizontal axis interval determined in step 4.1;

[0112] If the length of the first detection curve in the horizontal axis interval is within the calibrated length range of 13-48mm of the current weld to be inspected, and at the same time, the maximum change of the magnetic induction intensity on the vertical axis is greater than the minimum magnetic induction intensity threshold of 5000nT corresponding to the current material and less than the maximum magnetic induction intensity threshold of 50000nT corresponding to the current material, the above defect is determined to be a weld defect;

[0113] Specifically, Figure 7 : is a curve diagram of the change of magnetic induction intensity of the weld detected when the base material is martensitic stainless steel in the embodiment of the present invention; Figure 7As shown, curve 1 is the magnetic field signal of the first detection coil 22 in the sensor array, and curve 2 is the magnetic field signal of the second detection coil 23 in the sensor array. By comparing the trend of the two detection curves through the change of the slope, according to the change of the slope of the first detection curve and the second detection curve, it is determined that there are two defects in the magnetic field signal of the weld causing magnetic anomalies. The length of the two defects in the horizontal axis interval is within the calibrated length range of 13mm-48mm of the current weld to be inspected, and at the same time, the maximum change of the magnetic induction intensity ΔB on the vertical axis is greater than the minimum threshold value of the magnetic induction intensity corresponding to the current material, 5000nT, and less than the maximum threshold value of the magnetic induction intensity corresponding to the current material, 50000nT, so the above two defects are determined to be weld defects.

[0114] Step 5: Determine the location of the weld defect according to the horizontal axis interval corresponding to the weld defect.

[0115] Specifically, the defect magnetic anomaly area determined in step 4 is marked with a rectangular frame to indicate the magnetic anomaly horizontal coordinate span range and the vertical coordinate magnetic induction intensity variation range, and the defect position information is read according to the horizontal coordinate corresponding to the rectangular frame. It can be obtained that the spans of the two defect magnetic anomalies in the weld are 46mm-73mm and 144mm-175mm respectively.

[0116] Figure 8 The actual defect position information of the weld of martensitic stainless steel obtained by radiographic filming in the embodiment of the present invention is as follows: Figure 8 As shown, after verification by X-ray filming, the location and situation information of the actual defect are in good consistency with the detection results of the fusion weld defect detection device based on magnetic field signal measurement proposed by the present invention.

[0117] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0118] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A weld defect detection probe based on magnetic field signal measurement, used to detect weld defects of ferromagnetic materials or weak magnetic materials, characterized in that: It comprises a detection housing (1) and a sensor (2) installed in the detection housing (1); The sensor (2) comprises a detection core (21), a first detection coil (22), a second detection coil (23), a first signal line for outputting a magnetic field signal of the first detection coil (22), and a second signal line for outputting a magnetic field signal of the second detection coil (23); the first signal line and the second signal line are used to respectively connect to an external industrial computer (3); The detection magnetic core (21) is arranged close to one end of the detection housing (1); The first detection coil (22) and the second detection coil (23) are sequentially wound around the detection magnetic core (21) in a direction from one end of the detection housing (1) to the other end of the detection housing (1); a mutual interference-free distance a is provided between the first detection coil (22) and the second detection coil (23); the mutual interference-free distance a is used to avoid mutual interference between the magnetic field signal of the first detection coil (22) and the magnetic field signal of the second detection coil (23); The first detection coil (22) and the second detection coil (23) have the same length and the same winding direction; The detection housing (1) is provided with an adjustment button (11); The action end of the adjustment button (11) extends into the detection housing (1) and is used to tighten the detection magnetic core (21).

2. The fusion weld defect detection probe based on magnetic field signal measurement according to claim 1 is characterized in that: The length of the first detection coil (22) and the second detection coil (23) is 5 mm-7 mm.

3. The fusion weld defect detection probe based on magnetic field signal measurement according to claim 2 is characterized in that: The adjustment button (11) is a nylon screw; The nylon screw is threadably connected to the detection housing (1).

4. The fusion weld defect detection probe based on magnetic field signal measurement according to claim 3 is characterized in that: The detection housing (1) is also provided with a detection switch (12); The detection switch (12) is mounted on an end of the detection housing (1) away from the detection magnetic core (21), and is connected to an external industrial computer (3) via a control line, and is used to control the on and off of the first signal line and the second signal line.

5. The fusion weld defect detection probe based on magnetic field signal measurement according to claim 4 is characterized in that: The material of the detection switch (12) is austenitic stainless steel.

6. The fusion weld defect detection probe based on magnetic field signal measurement according to claim 4 is characterized in that: The detection housing (1) comprises a detection portion (13), a clamping portion (14) and a cable portion (15) which are connected in sequence and have increasing diameters in sequence; One end of the detection magnetic core (21) is located in the detection portion (13), and the other end extends into the clamping portion (14); The adjustment button (11) is mounted on the clamping portion (14) and is close to the detection portion (13); A cable buckle (151) is provided in the cable portion (15); the cable buckle (151) is fixed to the inner wall of the cable portion (15) and is used to lock the first signal line, the second signal line and a control line connected to the detection switch (12).

7. A fusion weld defect detection device based on magnetic field signal measurement, characterized in that: It comprises an industrial computer (3) and a weld defect detection probe based on magnetic field signal measurement as claimed in any one of claims 1 to 6; The first detection coil (22) and the second detection coil (23) are used to collect magnetic field signals of the weld; The first signal line and the second signal line are respectively connected to the industrial computer (3) via aviation plug terminals; The industrial computer (3) is used for processing the magnetic field signal.

8. A method for detecting weld defects based on magnetic field signal measurement, based on the weld defect detection device based on magnetic field signal measurement according to claim 7, characterized in that: The following steps are involved: Step 1, place the detection probe perpendicular to the surface of the weld to be detected, and move the detection probe at a constant speed along the detection path for scanning to obtain a first detection curve of the first detection coil and a second detection curve of the second detection coil; the detection path is set along the length direction of the weld to be detected; the abscissa of the first detection curve and the second detection curve are both the length of the detection path, and the ordinate is both the magnetic induction intensity; Step 2: judging whether there is a defect according to the first detection curve and the second detection curve; 2.

1. Determine the causes of the magnetic signals of the first detection curve and the second detection curve: When the absolute values ​​of the slopes of the same horizontal coordinate of the first detection curve and the second detection curve in any horizontal coordinate interval are both less than the fixed value k or the absolute values ​​of the slopes are greater than the fixed value k, it is determined that the magnetic signal in the horizontal coordinate interval is caused by residual stress; the fixed value k is determined by the comparison test block; When the absolute value of the slope of the first detection curve in any horizontal axis interval is greater than the fixed value k, and the absolute value of the slope of the second detection curve in the horizontal axis interval is less than the fixed value k, it is determined that the magnetic signal in the interval is caused by a defect; 2.

2. Determine whether the defect is a weld defect: The defect is within the horizontal axis interval determined in step 2.1; If the length of the first detection curve in the horizontal axis interval is within the calibration length range of the currently inspected weld, and at the same time, the maximum change in the magnetic induction intensity on the vertical axis is greater than the minimum threshold of the magnetic induction intensity corresponding to the current material and less than the maximum threshold of the magnetic induction intensity corresponding to the current material, it is determined that the defect is a weld defect; the calibration length range of the currently inspected weld is determined according to the thickness of the inspected weld; Step 3: Determine the position of the weld defect according to the horizontal coordinate interval corresponding to the weld defect.

9. The method for detecting fusion weld defects based on magnetic field signal measurement according to claim 8, characterized in that: The step 1 also includes a step of fine-tuning the relative position of the sensor in the detection probe and the detection housing before detection; In step 1, the detection path includes at least one single detection path, and the calibration method of the single detection path is specifically as follows: the single detection paths are calibrated sequentially along the length direction of the weld to be detected, and the length range of each single detection path is 100mm-200mm. A repeated detection area is provided between two adjacent single detection paths, and the repeated detection area is greater than or equal to 1 / 3 of the length of the single detection path.

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